The present invention relates to a switch device of the type comprising:    a casing, in which a plurality of conductive tracks are fixed,    an operation element which is arranged so as to be able to move in translation in the casing along an activation axis,    a conductive dome-like member which is arranged in the casing and which is resiliently deformable, under the action of the displacement of the operation element, between a rest state corresponding to a first state of commutation of the device and at least one deformed state corresponding to a second state of commutation of the device,    a light source and    at least two power supply tracks for the light source, which tracks are fixed in the casing.
Switches of this type are known in the prior art and are sometimes referred to as “dome type switches”, in which the light source (generally a light-emitting diode or LED) is fixed to the casing. The light source generally comprises pins which are soldered to power supply tracks fixedly joined to the casing.
In such devices which are in particular used in producing keypad type switches of electrical devices, a translucent button which is fixedly joined to the operation element covers the light source. The device is activated by a user pressing on the translucent button in such a manner that the position of the translucent button with respect to the light source varies in accordance with the commutation state of the switch device.
In the case, for example, of a light source which is permanently supplied with power, whatever the state of the switch device, the user may perceive a variation in the luminosity of the source when the button is depressed.
The object of the invention is to overcome this disadvantage and the invention relates to a switch device of the above-mentioned type, in which changes in the state of the device, or more generally the displacement of the operation element in the casing, do not bring about any variation in the luminosity of the source, as perceived by the user.